1. Field of the Invention
The present invention relates to a method of maintaining database integrity that is used by multiple vehicles, and, more particularly, to a method of improving the integrity of a database that is used by multiple vehicles.
2. Description of the Related Art
The introduction of global positioning systems (GPS) in vehicles such as trucks and automobiles has enabled a large number of such vehicles to simultaneously use a common database, such as a database for use in navigation. The GPS determines the real-time location of each vehicle, and each vehicle may individually access the navigation database in order to retrieve information to assist the driver of the vehicle in ascertaining a desired route to his destination from the vehicle's real-time location.
A problem with this type of system is that it is difficult to keep the database up to date with the latest road construction projects that directly affect the choice of possible routes, or even the existence of the routes. Map data is generally updated sporadically and thus can be unreliable, i.e. not maintaining integrity. Another problem is that the optimal route may be a function of time-variant variables that cannot be maintained in the database due to the frequent change in these variables. Such time-variant variables may include weather conditions and traffic conditions at specific locations. Thus, a route to a destination may be selected based solely on variables that are relatively time-invariant, such as the locations of roads. However, the optimal route may depend heavily on time-variant variables that are not in the database, such as traffic conditions.
Yet another problem is that, even if it were possible to update the database in real time, not all data that would be collected by vehicles would satisfy integrity. For instance, individual vehicles could have faulty sensors or faulty GPS devices, or could travel “off-road” in areas in which other drivers would not want, or would not be able, to drive. Thus, if the database were updated in real-time with data collected from vehicles, the integrity of the database would suffer due to the bad data that would inevitably be collected for inclusion in the database.
What is needed in the art is a method of maintaining a database for use by multiple vehicles in such a way that integrity of both time-variant and time-invariant data in the database is protected.